Among so-called protein foods which contain proteins as essential components thereof or are eaten to ingest proteins, the thermally-gelled protein foods vary in quality, size and shape. In order to produce these thermally-gelled protein foods, it is required to chop, grind and mix the raw material.
In chopping, grinding and mixing processes of the raw material, it is required that the raw material is chopped as finely as possible so that as much proteins contained as possible may be extracted from cells of the raw material and auxiliary materials be as uniformly as possible dispersed in the raw material to function as effectively as possible to the extracted protein. Consequently, with proteins fuctioning to a maximum extent, the products is improved in binding properties and water-retention properties thereof. In case that such processes are not effectively conducted, it is not possible to obtain high-quality thermally-gelled products. Namely, the products are poor in binding properties and water-retention properties to result in poor-appetite.
These chopping, grinding and mixing processes suffer from many problems. For example, muscular fiber size and tenderness of the meat vary depending on cuts, sex, age, breeds and species of the slaughter animals. Consequently, when different kinds of meat are directly processed together through meat-treating machines, it is not possible to obtain good meat products with uniform particle size. Therefore, in case that different kinds of meat are employed as the raw material for the meat products, it is necessary that the different kinds of meat are differently chopped coarsely in a first stage followed by a common second stage in which the coarsely chopped different kinds of meat are further chopped together as finely as possible. This means a plurality of stages are required there.
In addition, in the chopping, grinding and mixing processes, the raw material is subjected to an external force and there is generated a frictional heat. In general, proteins are non-reversibly denatured when heated, to become denatured proteins. Accordingly, it is necessary to suppress the generation of heat as effectively as possible. However, this is not possible in the prior art, and, therefore, hitherto it has not been possible to sufficiently conduct these chopping, grinding and mixing processes. As a result, in the prior art, it is not possible for proteins to sufficiently function in manufacturing the meat products. In manufacturing the meat products, high-grade raw material may be effectively employed without any problem. In contrast with this, lowgrade raw material such as sinewy meat or the like containing some components which prevent thermal gellation is either impossible to be employed in many facturing of the meat products or brings about meat products poor in quality, even if employed.
In the prior art, since it is not possible to sufficiently conduct the chopping, grinding and mixing processes, a considerable amount of auxiliary raw material such as salt and the like must be added to the raw material even when the high-grade raw material is employed. However, this undesirably provides such foods as containing salt at a high level unhealthful. The present invention dissolves at a stroke the above problems involved in the chopping, grinding and mixing processes of the animal meat, fish meat and beans and provides such method and apparatus that evable the raw material to be chopped, ground and mixed continuously and in a short time to give fine particles of ideal size without denaturing the proteins at all.